The present invention relates to a tab of a terminal fitting, which is inserted into an electric contact portion of a female terminal fitting, for connecting an electric wire to the female terminal fitting.
Generally, as shown in FIGS. 6A to 7B, tabs 102a and 102b of male terminal fittings (hereunder referred to simply as male terminals) to be inserted into female terminal fittings serving as mating terminal fittings are formed by bending electrically conductive sheet metals. Thus, as illustrated in FIGS. 6A to 7B, curved surfaces 131a and 131b each having a radius of curvature, which is nearly equal to the thickness of the sheet metal 120, are formed on side portions of the tabs 102a and 102b. 
Meanwhile, for example, when a tab 120c, which has a structure similar to that shown in FIGS. 7A and 7B and is 0.64 mm thick and 0.6 mm wide, is formed, the radius of curvature of the curved surface 131c placed at each of corners thereof becomes large, as illustrated in FIG. 8. Moreover, flat surfaces 135c, each of which is placed between the corresponding curved surfaces 131c, become narrow.
Further, when the tab 102c is inserted into a cylindrical electric contact portion 106 of the female terminal 103 as shown in FIG. 9A, contact portions 107a of a pair of resilient pieces 107 of the female terminal 103 come into contact with the flat surfaces 135c, respectively. The pair of resilient pieces 107 generates an elastic restoring force acting in a direction in which the tab 102 is sandwiched therebetween. The tab 102c is restrained from going out of the electric contact portion 106.
In the case that the tab 102c is misaligned with respect to the contact portions 107a in the electric contact portion 106 at that time, as illustrated in FIG. 9B, the contact portions 107a may face the curved surfaces 131c in such a way as to come into contact therewith. In this case, the elastic restoring force of each of the resilient pieces 107 becomes weak, so that the tab 102c easily goes out of the electric contact portion 106 of the female terminal 103.
Accordingly, an object of the invention is to provide a tab of a terminal fitting, which can be prevented from going out of an electric contact portion of a mating terminal fitting.
To eliminate the drawback of the conventional tab and achieve the foregoing object, according to the invention, there is provided a terminal fitting tab (hereunder referred to as a first tab), which is adapted to be inserted into a cylindrical electric contact portion of a mating terminal fitting and to be urged by resilient pieces of the counterpart terminal fitting thereby to be restrained from going out of the electric contact portion. This tab is formed by bending an electrically conductive metal sheet. The metal sheet comprises a part including portions, which are brought into contact with the resilient pieces when the tab is inserted into the electric contact portion, and the remaining parts. In the case of this tab, the metal sheet is formed so that the thickness of the part including the portions to be brought into contact with the resilient pieces is less than the thickness of the remaining parts.
According to an embodiment (hereunder referred to as a second tab) of the first tab of the invention, the metal sheet is formed so that the part including the portions to be brought into contact with the resilient pieces has a concave portion formed by denting one surface thereof, and that the other surface placed in back of the one surface of the part including the portions to be brought into contact with the resilient pieces is formed in such a manner as to be flush with corresponding surfaces of the remaining parts.
According to an embodiment (hereunder referred to as a third tab) of the second tab of the invention, the tab is formed by bending the metal sheet so that the one surface of the part including the portions to be brought into contact with the resilient pieces is inwardly placed, and that the other surface thereof is outwardly placed.
According to the first tab of the invention, the metal sheet to be bent in such a way as to constitute the tab is formed so that the thickness of the part including the portions to be brought into contact with the resilient pieces is less than the thickness of the remaining parts. Thus, when the tab is formed by bending the metal sheet, the radius of curvature of each of curved surfaces formed on corners of the part including such portions is small.
According to the second tab of the invention, the part including the portions to be brought into contact with the resilient pieces has a concave portion formed by denting one surface thereof. Moreover, the other surface placed in the back of the one surface of the part including such portions is formed in such a manner as to be flush with corresponding surfaces of the remaining parts. Thus, the part including the portions to be brought into contact with the resilient pieces is reliably formed in such a way as to have a thickness that is less than the thicknesses of the remaining parts.
According to the third tab of the invention, the metal sheet is bent so that the one surface of the part including the portions to be brought into contact with the resilient pieces is inwardly placed, and that the other surface thereof is outwardly placed. Thus, the radius of curvature of each of curved surfaces formed on corners of the part including such portions is small. In addition, portions of such a part, which respectively face the resilient pieces, are formed in such a manner as to be flush with corresponding surfaces of the remaining parts. This facilitates the contact between such portions and the resilient pieces.